Rolling element bearings, such as ball bearings, are known in a variety of applications for the mounting of shafts and other rotatable machine components, particularly in vehicle transmissions. The ball bearings are positioned between inner and outer rings, which have grooves for receiving and guiding the ball bearings. Deep-groove ball bearings (DGBB) are known to be used in high-performance applications.
In high-speed applications such as continuously-variable transmissions (CVT), hybrid transmissions, e-axles, and electric vehicles, a DGBB experiences relatively high speed, load, and temperatures. In these conditions, problems of creep and wear can lead to debris production and eventual bearing failure. The housing of the transmission, at its interface with the outer ring, may be particularly susceptible to creep and is often formed of a softer material than the DGBB. However, creep may cause damage to either part of the housing/outer ring interface or either part of the shaft/inner ring interface, especially at high operating temperatures. Previous solutions include specialized coatings and/or angular contact bearings implemented in conjunction with a spring load device that compensates for a loss of preload due to thermal expansion of the housing. These solutions are significantly more expensive and complicated than a standard DGBB.
The number of balls in a DGBB directly correlates to a bearing assembly's performance, but is necessarily limited by the assembly method and space constraints within the transmission. Likewise the radial thickness of bearing rings correlates to improved performance subject to space constraints.